Air cooled centrifugal water chillers per se are known in the art, as exemplified by U.S. Pat. No. 3,857,253. Prior attempts to operate chillers of this type under low outdoor ambient conditions, however, have not relied upon flooding of the air cooled condenser in order to reduce its capacity at the low outdoor ambient temperatures and, instead, a selectively operable refrigerant pump has been provided between the air cooled condenser and evaporator in order to insure the passage of refrigerant therebetween at low ambients.
In U.S. patent application Ser. No. 972,309, filed concurrently herewith, in the names of Mark O. Bergman, John W. Leary, Duane F. Sanborn, and Chester D. Ware, which application is commonly assigned with the present application, an air cooled centrifugal water chiller is disclosed which includes a water cooled heat recovery condenser for the production of a heated liquid. In the system disclosed therein, the evaporator shell is simply made sufficiently large to hold the quantity of refrigerant required to flood the air cooled condenser during full heat recovery operation. The subject matter of said application is hereby incorporated herein.